1. Field of the Invention
The present invention relates to a lifting device, and more particularly to a lifting apparatus of adjusting spaced-apart tines to fit a load depending on fork pocket spacing and height of the load.
2. Brief Description of the Prior Art
Fork tines have been used for lifting and moving a load. Typically, fork tines mounted on a frame of a lifting apparatus are spaced-apart from each other. Because a height of the frame fixed, the lifting apparatus is limited to use for lifting and carrying a fixed-sized load. A plurality of lifting apparatuses or a bulky and complicated lifting apparatus have been used for various sized loads.
Moreover, depending on various sizes of the height and the length of the loads, the lifting apparatus having one dimensional adjustment is not enough to lift and move the various sized loads. Furthermore, due to the fork tines being shorter than width of a flatbed trailer, access to containers on the opposite side of the flatbed requires additional time and space to maneuver the forklift.
In efforts of adjusting the distance between fork tines or a height of the frame in the lifting apparatus, U.S. Pat. No. 5,984,050 for a Carriage Suspension For Lift Truck issued to Ronald, U.S. Pat. No. 5,829,948 for a Multipurpose Lift Apparatus and Method issued to Becklund, U.S. Pat. No. 5,758,747 for a Mast Support for Forklift issued to Okazaki et al., U.S. Pat. No. 5,722,511 for a Lifting Vehicle and Method of Operating the Vehicle issued to Wakamiya, U.S. Pat. No. 5,586,619 or a lifting Apparatus issued to Young, U.S. Pat. No. 5,509,774 for a Load Clamping apparatus with an Increased Extent of Vertical Movement issued to Yoo, U.S. Pat. No. 4,657,471 for a Load Lifting Unit For a lift Truck issued to Shinoda et al. disclose various types of lifting apparatuses having the fork tines. These references, however, show mechanisms adjusting only one dimension of the fork tines depending on the size of the load or complicated mechanisms adjusting one or two dimensions of the fork tines and including a tractor or a truck.
In efforts of maintaining the balance of the lifting apparatus, U.S. Pat. No. 4,585,268 for a Overhead Guard For Lift Trucks Of Different Length issued to Downing, U.S. Pat. No. 4,580,650 for a Industrial Truck issued to Matsuda, and U.S. Pat. No. 4,502,709 for an Articulated Loader With Transversely Displaceable Counterweight issued to Schaeff disclose various types of counterbalance using a lifting truck. These references, however, fail to show the counterbalance used in a lifting apparatus lifting loads or containers accessed only from one side of the loads to be picked up and moved to a staging area with the use of a crane.
Regarding screw jack mechanisms, U.S. Pat. No. 5,118,082 for a Electrical Operated Screw-Type Jack issued to Byun, U.S. Pat. No. 4,641,813 for a Dual Automobile Jack For Consumer Use issued to Arzouman, and U.S. Pat. No. 4,609,179 for a Screw Jack issued to Chem et al. disclose typical structures of screw jacks. These references, however, do not show any application for a lifting apparatus.
Therefore, we have noticed that the conventional method and apparatus fail to show a lifting device having a variable range of frame height, tine spacing, and tilt angle of the fork tines. Moreover, when the various sized loads should be located in a limited space or a designated storage location, and are accessed only from one side of the loads to be picked up and moved to a staging area with the use of a crane, the conventional lifting apparatus cannot move within the space and carry the various sized loads into the limited space.
It is an object of the present invention to provide a lifting apparatus suitable to lift and carry all various sized loads.
It is another object of the present invention to provide a lifting apparatus able to load a container into a limited space and a designated storage location.
It is yet another object to provide a lifting apparatus able to adjust any height of a frame or a distance between fork tines.
It is still yet another object to provide a lifting apparatus able to balance when lifting and moving the load accessed only from one side of a flatbed trailer.
It is a further object to provide a lifting apparatus able to access a load within a minimum amount of aisle space.
These and other objects may be achieved by providing a lifting apparatus including a horizontal framework, a telescoping mast coupled to one side of the horizontal framework, a telescoping mast unit having upper, middle, and lower telescoping mast assemblies, and a pair of fork tine assemblies movably mounted on the lower telescoping mast assembly. The horizontal framework is coupled to an overhead bridge crane and is accessible to any load located within a minimum amount of aisle space. A counterbalance is mounted on the other side of the horizontal framework.
The horizontal framework includes a pair of horizontal supporters spaced-apart from each other. Connectors formed on horizontal framework are attached to a bridge crane trolley by securing to the hooks or twist lock connectors of the bridge crane trolley into the connectors.
An electric motor mounted on the horizontal framework is connected by a shaft to an assembly of power screws. The other end of the vertical screw is inserted into a fixed nut on the middle mast assembly.
Upper mast assembly is mounted beneath of the horizontal framework and includes two upper vertical beams spaced-apart from each other and two upper horizontal side bars attached to the spaced-apart upper vertical beams to maintain a distance between the spaced-apart upper vertical beams. Pairs of rails are formed on the upper vertical beams. The vertical screws are rotatably mounted on the upper mast assembly.
A middle mast assembly coupled to the vertical screw of the upper mast assembly through the fixed nut includes two middle vertical beams spaced-apart from each other and two middle horizontal beams attached to spaced-apart middle vertical beams to maintain a distance between the spaced-apart middle vertical beams. Two pairs of rails formed on the two middle vertical beams have a telescoping relationship with each pair of rails of the upper vertical beams.
A lower mast assembly includes two lower vertical beams spaced-apart from each other and lower horizontal beams, each end coupled to the spaced-apart lower vertical beams. A lifting chain is coupled to both the upper and lower mast assemblies through a pulley rotatably mounted on the middle horizontal beam of the middle mast assembly. An anchor is secured to the lower horizontal beam. The lifting chain has one end connected to the anchor and the other end connected to the upper horizontal side bar of the upper mast assembly while a portion of the lifting chain is wound around a peripheral surface of the pulley. A fork tine assembly is mounted on the lower mast assembly, and two fork tines are spaced-apart from each other by a pair of tine drive motors mounted on the lower mast assembly.
The combined upper, middle, and lower mast assemblies are tilted from the vertical position with the use of two tilt drive power screws. These power screws are rotatably mounted on the horizontal framework. Mechanical power is supplied to the screws through an electric motor and shaft mounted on each side of the horizontal framework. The other end of each tilt drive power screw is rotatably attached to the lower end of the upper mast assembly vertical beams.